The Lankavatara Sutra has expounded the many faults of eating meat. We will only discuss the three major ones here. The first is that all sentient beings have been parents to one another since beginningless time. As such, the animals that we eat today surely have once been our parents too. Eating these meat will be like eating the flesh of our own parents or children. It is therefore a wrong thing to do even from the mundane perspective, let alone the supramundane point of view.

[Excerpt from Luminous Wisdom Book Series 1: The Right View ~Why Vegetarian?]

Offering of Dharma (during life liberation): Secondly, feed them nectar pills. The use of nectar pills is not emphasized in exoteric Buddhism, but very much so in Vajrayana. Most of the nectar pills were originally handed down by Guru Rinpoche and later discovered by real tertons, finders of terma (hidden treasures). It should be noted that not all nectar pills have beneficial effect.

[Excerpt from Luminous Wisdom Book Series 1: The Right View ~ Liberating Living Beings]

According to the Theravadin Vinaya, during the time of the Buddha, there was a layperson, a village head, who had many hunters working as his subordinates. Before he was enlightened, the hunters used to offer him large amount of meat from their hunt. After receiving some teachings from Shakyamuni Buddha, he eventually attained realization of the Hinayana path of seeing and stopped eating meat. However, his subordinates continued to hunt and offer him meat. He would instead offer the meat to the monastics whenever they came begging for alms.

[Excerpt from Luminous Wisdom Book Series 1: The Right View ~Why Vegetarian?]

Some of the so-called nectar pills are not only devoid of any merit but can also bring harm if taken, such as preventing one from attaining liberation in future lives and creating hindrances to liberation. Where do these harmful pills come from? Some are from tertons who are actually impostors and some are concocted by demons to hurt sentient beings. At times, genuine nectar pills, after being handled or made by persons who have broken samaya vows, can also be tainted. As Guru Rinpoche did not leave behind many nectar pills, accomplished masters, after retrieving them, will mix them with other nectar and medicinal herbs, then bless the pills through meditation and mantra recitations. If during this process there is one samaya violator among the attending practitioners, the pills will get tainted.

[Excerpt from Luminous Wisdom Book Series 1: The Right View ~ Liberating Living Beings]

What are the definitions of the three kinds of clean meat? First, I did not see with my own eyes that the animal was killed for me; second, I did not hear from someone I trust that it was killed specifically for me; third, I myself have no doubt that it was not killed specially for me. For example, the meat sold at the market is for all meat eaters, not for me alone, so it is to be deemed clean meat. Or, when being a guest of a Tibetan house, the hosts would usually kill a sheep to honor their guest. The Chinese would more likely want to kill chickens, fish, rabbits and the likes for the same occasion. These are not clean meat. The rule of Hinayana stipulates that only the three kinds of clean flesh are permitted for consumption; others are not.

[Excerpt from Luminous Wisdom Book Series 1: The Right View ~Why Vegetarian?]

Although freeing small fry or other beings that will not be killed in the near future is also liberating living beings, they are not lives saved at the point of being killed. To engender great merit and to be deemed a genuine form of fearless offering, lives saved should be those that are about to be killed such as the assorted fish sold in the marketplace.

[Excerpt from Luminous Wisdom Book Series 1: The Right View ~ Liberating Living Beings]

Mahayana Buddhism does not tolerate the consumption of any kind of meat. Not only those that do not qualify as being clean but also meat from the animals that died of illness. Where can we find proof of this view in the Mahayana canon? Mainly the Lankavatara Sutra and the Nirvana Sutra. There are others, but these two provide the most explicit explanation.

[Excerpt from Luminous Wisdom Book Series 1: The Right View ~Why Vegetarian?]

Offering of Dharma (during life liberation): Firstly, recite the various Buddha’s names or other mantras to the beings about to be released. According to the scriptures, these beings will be greatly benefited upon hearing the Buddha’s names and mantras. Also make sure that every one of them can hear the recitations. If we recite from afar and dedicate the merit to them afterward, they can be benefited somewhat but cannot obtain specifically the merit of hearing the Buddha’s names because they did not hear the recitations. If we recite within their hearing range, the merit they will receive are twofold: First, they will be the beneficiaries of our dedication. Second, by the merit of hearing the Buddha’s names and mantras, they can attain liberation from samsara. It does not mean that liberation can be attained in their next life, which ultimately depends on how serious their respective karmic hindrances are, but it should not take too long.

[Excerpt from Luminous Wisdom Book Series 1: The Right View ~ Liberating Living Beings]

While it is a fact that some practitioners in Tibet eat meat, it does not mean that all Tibetan practitioners do or that the scriptures condone this behavior. One cannot find anywhere in either the Mahayana sutras or the Vajrayana tantras that deem meat eating acceptable.
One thing does worry me though. Some practitioners from China who used to be vegetarian went to Tibet to study Vajrayana. Instead of learning the essence of Tibetan Buddhism, they adopted the bad habit of consuming meat, even to the point of being excessive sometimes. They believe this is the way of real Vajrayana, and that as a yogi of Vajrayana, eating meat is only right and natural.

[Excerpt from Luminous Wisdom Book Series 1: The Right View ~Why Vegetarian?]